Forrester Research recently came out with their Wave report reviewing 15 top Email Service Providers (ESPs). Summary here, full report can be downloaded from ExactTarget here.
The report has both ExactTarget and Responsys as being ranked at the top, with both being cited for providing robust and comprehensive offerings, excellent functionality and very good service to support their platforms. I've worked with both solutions and can attest to their power and flexibility.
Other notable ESPs mentioned include Yesmail, e-Dialog, Acxiom, Experian and Epsilon. Not ranking quite as high is Lyris, which I've also worked with. I feel Lyris is an up-and-comer in the space due to their solid analytics package, simple content creation, PPC management and burgeoning social media capabilities.
Some other interesting notes include that 92% of those surveyed for the report say they are actively using email marketing as part of their marketing mix and agree that spending on email marketing will be increasing in the next 3 years. So much for the death of email as a marketing tool.
Enhancing the business case for ESPs includes marketers offsetting staffing losses with the increased productivity and efficiency that ESPs provide, and an increased relevance in marketing programs.
I believe a great deal of that increased relevance is (and will continue to be) due to more and more companies embracing lead nurturing and a mutual value exchange in their interactions with new prospects. Email has become the de facto communications channel for timely, compelling and relevant interactions between company and prospects. As the ROI for email marketing for cold lists (list rental) continues to decline, the ROI on house lists/marketing databases should rise as marketers seek to build relationships through their communication by providing thoughtful, educational and targeted content that prospects seek out and come to expect.